1. Field of the Invention
The present invention relates to a solid-state image pickup device, a method of driving the same, a signal processing method for the same, and an image pickup apparatus.
2. Description of the Related Art
In a solid-state image pickup device, signal charges generated in a photoelectric conversion portion (light receiving portion) are transferred to a floating diffusion capacitor, and are converted into a voltage in the floating diffusion capacitor to be read out to the outside. However, it has been difficult to ensure the sufficient signal charges along with the recent miniaturization of pixels. For this reason, it has been difficult to obtain an output voltage having a sufficient magnitude from each of the pixels.
The output voltage V from the pixel is expressed by V=Q/C where C is a signal detection capacitance and Q is a quantity of signal charges corresponding to a signal originating from a received light. Therefore, the small signal detection capacitor C makes it possible to increase the output voltage V, that is, enhance the sensitivity.
For this reason, heretofore, a photoelectric conversion element having an end grounded, a common source configuration amplification transistor, a capacitive element having a small capacitance, and a reset transistor constitute a pixel, thereby realizing a high-sensitivity signal output. Here, the common source configuration amplification transistor has a gate electrode connected to the other end of the photoelectric conversion element, a source electrode grounded, and a drain electrode connected to a load circuit. The capacitive element is connected between the drain electrode and the gate electrode of the common source configuration amplification transistor. Also, the reset transistor is connected in parallel with the capacitive element. This technique, for example, is described in a Patent Document 1 of Japanese Patent Laid-Open No. Hei 5-207375.